The overall aim of this investigation is directed toward an understanding of the mechanism and control of membrane-associated energy-linked electron transport processes in microorganisms, as well as the regulatory properties of isocitrate dehydrogenases (IDH). Specifically, work will be continued to determine the roles of MK-9(2H), CoQ-9, and unknown quinones in electron transport in Mycobacterium phlei, Crithidia fasciculata, and Mycoplasma laidlawii, respectively. The water soluble complex from M. phlei containing MK-9(2H), which has been resolved into two fractions necessary to restore NADH oxidase activity light-inactivated electron transport particles (ETP), will be further characterized, particularly in regard to the possibility that the protein moiety may be a quinone binding protein. The role of NAD plus in stimulating and protecting the NADH oxidase in ETP against aging and heat will be investigated. The active compounds in the factor F2 will be isolated. The study of the coupling of electron transport to oxidative phosphorylation in C. fasciculata will be continued, using "modified" whole cells and isolated mitochondria that exhibit some degree of respiratory control. The study of biogenesis of this unusual mitochondrion and the proteins coded for by the mitochondrial DNA will be continued. The unusual cytoplasmic NAD plus-linked IDH from this organism will be studied further with emphasis on its allosteric properties, and the enzyme will be compared to that in the bloodstream and culture forms of Trypanosoma bruceii undergoing the "respiratory switch." The investigation of the regulation by nucleotides on a membrane-associated NADH oxidase in M. laidlawii will continue.